The scope of this proposed study is to demonstrate the efficacy of recombinant human lactoferrin (rhLF) to act as an immune modulator through T cell regulation in distinct murine models of inflammatory bowel disease (IBD) which best recapitulate Crohn's-like ileitis and colitis. Crohn's disease (CD) affects as many as 700,000 people in the United States, with current therapies relying on anti-inflammatories and immune modulators which are palliative at best, or expensive TNF antibody therapies, each of which have associated toxicities. Therefore, we propose to investigate the use of Ventria's rice-derived rhLF in preclinical models to demonstrate its efficacy as a cost effective therapeutic option in th treatment of CD. Lactoferrin (LF) is an endogenous anti-inflammatory molecule secreted at mucosal sites within the body. While originally identified as a key component of innate immunity because of its antimicrobial properties, increasing evidence points to the ability of lactoferrin to additionally modulate the adaptive immune system making it an ideal therapeutic target for chronic mucosal inflammatory conditions such CD. Our preliminary studies have effectively demonstrated the therapeutic potential of subcutaneous rhLF in a murine model of CD, thereby negating its direct interaction with the intestinal microbiota and toxins. Specifically, rhLF administration significanly decreased nave T cell infiltration and proliferation in the intestinal lamina propria, mesenteric lymph nodes and spleen of 20wk old TNF?ARE mice which, similar to CD patients, develop a spontaneous chronic transmural intestinal inflammation. rhLF-treated mice also exhibited improved histological indices and had improved intestinal barrier function, indicating efficacy for rhLF to decrease inflammation in a preclinical model of CD. Given the broad spectrum of disease phenotypes that CD encompasses, from mild to severe disease involving strict ileitis, colitis or both, it is prudent to validate these findings in multple preclinical models. Ventria Bioscience currently uses a rice expression system to produce recombinant human LF at high levels of purity at a cost-effective scale, and has demonstrated the safety and efficacy of rhLF in clinical trials when administered to human subjects. Based on the proven safety record of rhLF and the capacity within Ventria for large scale production of this recombinant protein, success in these phase I trials will allow us to rapidly translate these findings into a phase II clinical trial in pediatric patients. Nonetheless we must first demonstrat that rhLF remains effective when administered orally and more crucially validate the protective effect of rhLF in an additional preclinical model of CD. Specifically, we seek to investigate the following: Investigate the efficacy of oral rhLF in a relevant pre-clinical model of chronic CD, and demonstrate the mechanism of action of rhLF through its ability to enhance a pro-regulatory environment. Previous studies have used harsh and very acute chemical models of ulcerative colitis (UC) to demonstrate a protective effect of purified bovine or human LF, when orally administered. These studies did not attempt to demonstrate a clear mechanism of action of LF, nor do the models themselves recapitulate the human condition very well. Therefore, we will test the efficacy of oral rhLF to induce remission in a chronic model of TNF- driven ileitis (TNF?ARE), which best displays the hallmarks of human disease. We will investigate the role of rhLF in the regulation of specific T cell phenotypes characterized by their ability to exacerbate or suppress the inflammatory response. The activity of rhLF is not limited to a single pre-clinical model of CD, by further investigating its immunoregulatory role in a T cell mediated model of colitis. In an effort both to demonstrate that the effect of rhLF is not model-specific, ad to evaluate rhLF's efficacy a model of Crohn's-like colitis, a common feature of CD, we have chosen a T cell driven model of colitis (CD4+CD45RBhigh adoptive transfer model). In this model, we will test the ability for rhLF to regulate T cell populations from the earliest to pervasive staes of inflammation, with particular regard to the role of regulatory T cells (Tregs) and their abilityto suppress the pathogenic immune response. Together, these models will define an immunomodulatory role of rhLF in two distinct chronic models of CD, testing the hypothesis that rhLF exerts its protective effect in part by induction of a pro-regulatory environment within the intestine.